Resilient tire



EUG.' HULSE.

RESILIENT TIRE.

Feb. 20, 1923.

EILED DEC. 22. 1922.

Patented Feb. 2Q, i923.

ifiigtid F F l Q E e nnrson e. ii'ULsii, or Genesi-traire, aia-arman, Assrenon To KELLY-SPRINGFIELD Trancoiviranr, or cniiriaiiatann, viai-ternirNn, a conronarron or NEW Jiiasiir.

RESLIENT TIRE.

.Application ined December 22, 1922. Serial 1\To 608,452.v

To all whom t may concern:

Be it known that l, EDISON G. HULsn, a citizen of the United States, residing at Cumberland, in the county of lAllegany and State of AMaryland, have invented certain new and `useful Improvements in Resilient Tires, of which vthe following is a specilication.

My `present invention has for its object a speciiic improvement in the design vof that type of heavy-duty, nonpneumatic tire, principally usedon motor trucks and mainly dependent for resiliency upon the presence of stress-relieving voids in the structure into which the displaced material within the zone of traction'will flow. I

The novel improvements herein recit vil are particularly directed to-the further perfection of the type of tire shown generally. in Letters Patent No. 1,427,331 of August 29, 1922; thesaine representing a widely ad- -vertised and universally used tire known as the caterpillar, and hereafter,designated by that name. The chief` characteristic of this caterpillar7 tire being ,the presence of deep clefts or notches worlred in a particular-manner into the sides and partially across the tread face (with or without secondary voids of a specific form) for the purpose of increasing traction as well as affording means for relieving the displaced and highly stressed material of the tire within the traction zonethereby preventing the phenomena of cupping, all as explained in the aforesaid Letters Patent.

lItis unnecessary to burden this application with adetailed description `of the properties and characteristics of the caterpillar, tire, as the vrelation of the present iuvention to the `functional improvement of the caterpillar willfbe readily comprehended b v those well `skilled in the art.

. To facilitate the discussion of the pres- .ent improvements asvap'plied to the eaten pillar tire, attention is directed tothe peculiar manner4 of partially.l dividing the ltread byradial clefts or notches into a blocks, whiclnwith the contributing support of the central portion of the tread surface, constitute the` weight-supporting portion in road contact. In the following discussion rthe above identifying terminology will, in general, be adheredsto;

In order to appreciate the application of my improvements to the performance of this tire, it is noted that the portiony of the tread traversed by a notch and the adjacent edges of the juxtaposed traction blocks, constitute a relatively soft non-weightbcaring area; Whereas, that portion of the traction blockintermediate the notches is relatively hard, and necessarily supports, in arestricted area, a greater load than that absorbed by the soft spot area. This distribution'of alternately soft and hard areas obviously yresults in a tire structure, which, in rolling, is subjected to stresses of 'varying `intensity, intermittently active, and highly detrimental; not only due to the complexity and intensity of localized stresses, but dynamicallyL adversely affects the smooth rolling properties of the tire with its consequential effect upon thevehicle on which it is mounted.

rlhe actual practical result of the presence of soft and hard areas-quite aside from the deleterious effect of the consequential varying stresses set up within the structure itselfis a. tendency of the tire to run bumpy, With wide notches, and relatively narrow intact tread surface areas between, the action of the structure would be noticeably rough to an observer riding` on the vehicle. l/Vith, narrower notches, and relatively more extensive intermediate intact tread areas', the tendency to bump would still exist in a diminishing degree, but still be actually present and only absorbed by the secondary dampening reaction of inechanicalvibration absorberssuch as the customary spring'suspension onthe vehicle itself.

vBeing well cognizant of the defect to be overcome, it has` become the specific object ltial flexibility. double series of semi-independent traction' A specific object ofthe novel formation of the sub-tread voids is to insure that the relieved area will freely respondy to delicotion,v under -vcasual and inconsiderably stresses, butv will progressively stiften as deformation increases under an increment of load,vthus restricting the ultimate deformation of the tire.

ll() Y Another object of the sub-tread void is its formation tending to progressively elongate circunii'erentially of the tire under increasing load, thereby extending the area of resiliency under the aforesaid hard spots.

A further object is to so proportion and direct the sub-tread voids that road accretions will not be encountered, and that the internal mass shall become ventilated whereby the heat generated by deformation and working under load will be harmlessly radiated, and whereby during the heat treat-- ment, the vulcanizing temperature shall be conveyed `intimately within the central mass.

A still further object is to so proportlon and design the subtread void that fatigue lilies of weakness in the presence ot extreme deformation shall be avoided.

Andinally, to so combine, relate and coordinate the old `features with the new and novel improvements that new functional attributes will be'incorporated into the environment structure to a highly beneiicial de ree.

`hese, and other objects will hereafter be further illustrated and explained in the ac companying drawings, specifications and claims.

Fig. l, shows a partial perspective ot' one form of my invention, the sub-tread void being arched similar to a semi-elliptic spring.

F ig. 2, is similar to Fig. l, except that the void4 is fashioned similar to a full-elliptic spring.

Fig. 3, is a lateral section through the plane III-III ot' Fig. 2, showing the internal aspect of the sub-tread void.

In the drawings, numeral l() represents the conventional resilient tire mass having traction notches Vll worked therein suiciently deep and extensive to materially relieve the traction wave and improving the tractive features. The novel voids 12 are shown ot' a basic type to accomplish the desideratum claimed, and the usual metallic rim on which this type tire is manufactured is indicated as 13.

Particular attention is invited to the arched form of that portion of the void l2 nearest the tread and directly under the central ortion of the tread bloclqand to the rounded endings of its major axis; for the purpose now explained.

It is obvious that the convex crown of the sub-tread void constitutes the most effective geometrical form for absorbing loads without collapse. It is likewise apparent that the particular shape of this void, lying Within a, yielding resilient mass, will, in its reaction, simulate thedetlection of a well disigned elliptic spring member. This is due to the fact that the displaced rubber does not compress, but Hows, and to the further i'fact that the center of the load falls on the crown of the arch with gradual diminution of its intensity progressing away from that point and toward the major axis limits 0f the voids, whereby the reaction of the displaced material, when reacting under the controlling influence of the crowned void, will tend to deflect and elongate the void, as shown in dotted lines 14;. The facility with which this elongation of the void is effected is accounted for by reason of the comparatively small percentage or the load borne by that part oi the structure adjacent the endings oi the long dimension of the void; the reliei1 of load stress being due the proximity of the tread notches.

The above defined condition clearly indicating the inevitable and beneficial elongation of the sub-tread voids whereby the area of resiliency is progressively extended under increment of load. Thus, not only imparting new resilient properties to the entire structure, but, at the same time, affording means for absorbing the pent-up flow of the highly stressed tire structure whereby internal stresses are relieved and the resulting heat effectively and harmlessly dissipated.

To insure that there will be ample intact material lett within the central mass of the tire to transmit the enormous circumferential torque set up on the driving tires of the vehicle, it is noted that the sub-tread voids do not completely penetrate the tire, and that they are staggered in their opposed relation. In the preferred arrangement they penetrate approximately to the median plane ott the structure, with well rounded endings; and, in a direction circumferential of the tire, they are terminated short of the projected radial boundaries of the tread notches. The above arrangement and pro-k portions insure that the interior of the structure will be strong enough to stand upto its work.

It is also apparent that the combination of tread notched and sub-tread voids of the specific design will jointly contribute to the imparting to the structure of an unusual. degree of circumferential fiexibility. This being a great advantage t0 a tire in the starting of traction when the en ine is suddenly clutched in, for, it frequent y happens that enough power is applied to internally rupture a stili tire, or to strip it from its base anchorage. In a tire made as flexible as mine there will be a very considerable yield of the material when traction is sought under heaving driving torquethereby enabling a gradual absorption of the stress without sudden shock.

In the preferredarrangement of the combined old and new elements of my design, I prefer that the traction notches be staggered, thereby attaining a like relation of the' traction blocks and the sub-tread voids with each opposedsimilar member, respectively. It is likewise preferred that the v tire present a trapezoidal cross sectional form with its narrower surface transversely iiat and constituting the tread portion.

The above characteristics, and those previously especially referred to,'constitute the preferred form, the observance of which, it

- is believed, .would make for the highest eilicomprising: a body portion of trapezoidal y cross sectional formirremovably mounted on a metallic base' ring and having its narrower parallel face the tread portion; radially disposed traction notches uniformly spaced in staggered relation with opposed notches; `and sub-.tread voids partially traversing the internal tire mass from each side intermediintermediate the notch positions, said voids being arched toward the tread with a major axis circumferential of the said tire body portion and said voids being so proportioned v that the normal area of resiliency shall be load,

circumferentially extensible under without fatigue line weakness.

3. A lresilient tire of the class described, comprising a body portion of trapezoidal cross sectional form irremovably mounted on ametallic base ring and having its narrower parallel face the ltread portion; radi-` ally disposed traction notches uniformly spaced in staggered relation with opposed notches; and sub-tread voids partially traversing the internal mass from each side intermediate the notch positions, said voids being arched toward the tread whereby resistance to deformation is progressively re-v sisted as deformation increases and whereby the circumferential zone of resiliency is increased as the said arch fiattens under deforming stress,lwithout developing fatigue i line weakness.

4. A resilient tire of the class described, comprising: a body portion of trapezoidal cross sectional form irremovably mounted on a metallic base ring and having its narrower parallel face the tread portion; radially disposed traction notches uniformly spaced in staggered relation with opposed notches; and sub-tread voids partially traversing the internal mass from each side intermediate the notch positions, said voids terminating inwardly adjacent the median plane of the tire body, whereby an imperforate radial division of the structure is maintained in approximately the said median plane from rim to tread.

In testimony whereof I aiix my signature. 

